Post-manufacturing processes for submerged combustion burner

ABSTRACT

A portion of a submerged combustion burner is disposed into a pressure vessel. The portion of the submerged combustion burner has a welded area that has a first microstructure defined by a first number of voids. The vessel is filled with an inert gas, pressurized, and heated. Pressurizing and heating operations are performed for a time and at a temperature and a pressure sufficient to produce a second microstructure in the welded area of the burner. The second microstructure is defined by a second number of voids less than the first number of voids.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of pending U.S. application Ser. No.15/666,762, filed Aug. 2, 2017 which application is a divisional of U.S.application Ser. No. 14/824,981, filed Aug. 12, 2015, now U.S. Pat. No.9,751,792 issued Sep. 5, 2017.

BACKGROUND

In submerged combustion melting (SCM), combustion gases are injectedbeneath a surface of a molten matrix and rise upward through the melt.The matrix may include glass and/or inorganic non-metallic feedstockssuch as rock (basalt) and mineral wool (stone wool). Regardless of thematerial utilized, it is heated at a high efficiency via the intimatecontact with the combustion gases and melts into a matrix. Usingsubmerged combustion burners produces violent turbulence of the moltenmatrix and results in a high degree of mechanical energy in thesubmerged combustion melter. In this violent environment, the burnersare subjected to significant thermal and mechanical stresses that mayresult in increased likelihood of early failure.

SUMMARY

In one aspect, the technology relates to a method including disposing atleast a portion of a submerged combustion burner into a pressure vessel,wherein the portion of the submerged combustion burner has a firstmicrostructure defined by a first number of voids; filling the vesselcontaining the portion of the submerged combustion burner with an inertgas; pressurizing the vessel containing the portion of the submergedcombustion burner; and heating the vessel containing the portion of thesubmerged combustion burner, wherein the pressurizing and heatingoperations are performed for a time and at a temperature and a pressuresufficient to produce a second microstructure in the burner, wherein thesecond microstructure is defined by a second number of voids less thanthe first number of voids. In an embodiment, the portion includes atleast one of a burner body, a burner tip, and a burner base. In anotherembodiment, the temperature is in a range from about 2200 degrees F. toabout 3000 degrees F. In yet another embodiment, the temperature is in arange from about 2450 degrees F. to about 2750 degrees F. In stillanother embodiment, the temperature is about 2600 degrees F.

In another embodiment of the above aspect, the time is in a range fromabout 100 minutes to about 1000 minutes. In an embodiment, the time isin a range from about 200 minutes to about 600 minutes. In anotherembodiment, the time is about 365 minutes. In yet another embodiment,the pressure is in a range of between about 20,000 psi and about 50,000psi. In still another embodiment, the pressure is in a range of betweenabout 25,000 psi and about 40,000 psi.

In yet another embodiment of the above aspect, the pressure is about30,000 psi. In an embodiment, the method further includes weld-repairinga defect in the portion of the submerged burner before disposing theportion of the submerged burner in the pressure vessel. In anotherembodiment, the method further includes: removing the portion of thesubmerged burner from the pressure vessel; non-destructively testing theportion of the submerged burner for a defect; weld-repairing the defect;and returning the portion of the submerged combustion burner to thepressure vessel.

In another aspect, the technology relates to a method including:disposing a toroidal tip of a submerged combustion burner in a vise,wherein the toroidal tip has an average first surface roughness acrossan area of the toroidal tip; and polishing the toroidal tip of thesubmerged combustion burner to an average second surface roughnessacross the area of the toroidal tip, wherein the average second surfaceroughness is less than the average first surface roughness. In anembodiment, the area of the toroidal tip includes a plurality of initialsurface features having heights of about 10 microns to about 100 micronsprior to polishing. In another embodiment, the area of the toroidal tipincludes a plurality of polished features having heights not greaterthan 1 micron after polishing. In yet another embodiment, the area ofthe toroidal tip includes a plurality of polished features havingheights between about 1 micron and about 0.1 micron after polishing. Instill another embodiment the average second surface roughness is about5% of the first surface roughness.

In another embodiment of the above aspect, the average second surfaceroughness is about 1% of the first surface roughness. In an embodiment,the average second surface roughness is about 0.1% of the first surfaceroughness. In another embodiment, the polishing operation is performedsubstantially circumferentially. In yet another embodiment, thepolishing operation is performed randomly.

In another aspect, the technology relates to a system having: a meltvessel configured to receive a material and melt the material into amatrix, the melt vessel including: a base; a feed end wall defining afeed port for receiving the material; an exit end wall defining an exitport allowing egress of the matrix; and a roof, wherein the base, thefeed end wall, the exit end wall, and the roof form a substantiallyclosed volume; a transition channel in fluid communication with the exitport for receiving the matrix from the exit port; a plurality of burnersdisposed so as to penetrate the base, wherein at least one of theplurality of burners includes: a toroidal burner tip defining an outletfor delivering the combustion gases into the substantially closedvolume; a portion exposed to the matrix, wherein the portion of theburner exposed to the matrix includes a plurality of polished featureshaving heights not greater than 1 micron. In an embodiment, the portionexposed to the matrix includes the toroidal tip. In another embodiment,the portion exposed to the matrix includes a burner body. In yet anotherembodiment, the plurality of polished features has heights of less thanabout 0.5 micron.

In another aspect, the technology relates to a system having: a meltvessel configured to receive a material and melt the material into amatrix, the melt vessel including: a base; a feed end wall defining afeed port for receiving the material; an exit end wall defining an exitport allowing egress of the matrix; and a roof, wherein the base, thefeed end wall, the exit end wall, and the roof form a substantiallyclosed volume; a transition channel in fluid communication with the exitport for receiving the matrix from the exit port; a plurality of burnersdisposed so as to penetrate the base, wherein at least one of theplurality of burners includes a microstructure having a void fraction ofless than about 1%.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The same number represents the same element or same type of element inall drawings.

FIG. 1 is a longitudinal cross-section view of a burner.

FIGS. 2-11 are schematic longitudinal cross-sectional views variousexamples of submerged combustion burners.

FIGS. 2A, 6A, 7A, 8A, and 11A are detailed cross-sectional views ofvarious burner features described herein.

FIGS. 12A and 12B are a view and an enlarged view of a burner surface.

FIG. 13 depicts a method of polishing a portion of a burner aftermanufacture.

FIGS. 14A and 14B depict microstructures of a cast precious metalsamples before and after hot isostatic pressing processes, respectively.

FIG. 15 depicts a method of hot isostatic processing a portion of aburner after manufacture.

FIG. 16 depicts a schematic sectional view of a submerged combustionmelter system.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of various melter apparatus and process examples inaccordance with the present disclosure. However, it will be understoodby those skilled in the art that the melter apparatus and processes ofusing same may be practiced without these details and that numerousvariations or modifications from the described examples may be possiblewhich are nevertheless considered within the appended claims. Allpublished patent applications and patents referenced herein are herebyincorporated by reference herein in their entireties.

The technologies described herein relate generally to burners used in asubmerged combustion melter (SCM). In general, all burners require useof robust structure and materials so as to withstand mechanical andthermal stresses and fatigue while in the SCM environment. As such,material selection, manufacturing details, and post-manufacturingprocessing are all critical to help ensure a long service life of an SCMburner. The burners described herein, along with desirable materials,post-manufacturing processes, and so on, are uniquely suited to the SCMenvironment. SCM burners need not display all material, processing orfunctional properties described herein; however, it has been discoveredthat SCM burners having one or more of these characteristics can displaysignificant advantages over burners not so constructed. Burnersdisplaying many such characteristics display even greater advantages.Given the nature of the SCM process, very robust burners are desirableto avoid melter system downtime. FIG. 1 depicts a side sectional view ofa burner 1 that may be utilized in conjunction with the examples of thetechnology described herein. The burner 1 is a submerged combustionmelting (SCM) burner having a fluid-cooled portion 2 having a burner tip4 attached to a burner body 6. A burner main flange 8 connects theburner to an SCM superstructure or melter system, illustrated below.Burner body 6 has an external conduit 10, a first internal conduit 12, asecond internal conduit 14, and end plates 16, 18. A coolant fluid inletconduit 20 is provided, along with a coolant fluid exit conduit 22,allowing ingress of a cool coolant fluid as indicated by an arrow CFI,and warmed coolant fluid egress, as indicated by an arrow CFO,respectively. A first annulus 11 is thus formed between substantiallyconcentric external conduit 10 and first internal conduit 12, and asecond annulus 13 is formed between substantially concentric first andsecond internal conduits 12, 14. A proximal end 24 of second internalconduit 14 may be sized to allow insertion of a fuel or oxidant conduit15 (depending on the burner arrangement), which may or may not include adistal end nozzle 17. When conduit 15 and optional nozzle 17 areinserted internal of second internal conduit 14, a third annulus isformed there between. In certain examples, oxidant flows through thethird annulus, while one or more fuels flow through conduit 15, enteringthrough a port 44. In certain other examples, one or more fuels flowthrough the third annulus, while oxidant flows through conduit 15,entering through port 44.

Burners described herein may be air-fuel burners that combust one ormore fuels with only air, or oxy-fuel burners that combust one or morefuels with either oxygen alone, or employ oxygen-enriched air, or someother combination of air and oxygen, including combustion burners wherethe primary oxidant is air, and secondary and tertiary oxidants areoxygen. Burners may be comprised of metal, ceramic, ceramic-lined metal,or combination thereof. Air in an air-fuel mixture may include ambientair as well as gases having the same molar concentration of oxygen asair. Oxygen-enriched air having an oxygen concentration greater than 121mole percent may be used. Oxygen may include pure oxygen, such asindustrial grade oxygen, food grade oxygen, and cryogenic oxygen.Oxygen-enriched air may have 50 mole percent or more oxygen, and incertain examples may be 90 mole percent or more oxygen. Oxidants such asair, oxygen-enriched air, and pure oxygen may be supplied from apipeline, cylinders, storage facility, cryogenic air separation unit,membrane permeation separator, or adsorption unit.

The fuel burned by the burners may be a combustible composition (eitherin gaseous, liquid, or solid form, or any flowable combination of these)having a major portion of, for example, methane, natural gas, liquefiednatural gas, propane, atomized oil, powders or the like. Contemplatedfuels may include minor amounts of non-fuels therein, includingoxidants, for purposes such as premixing the fuel with the oxidant, oratomizing liquid fuels.

The fluid-cooled portion 2 of the burner 1 includes a ceramic or othermaterial insert 26 fitted to the distal end of first internal conduit12. Insert 26 has a shape similar to but smaller than burner tip 4,allowing coolant fluid to pass between burner tip 4 and insert 26, thuscooling burner tip 4. Various types of coolants are described below.Burner tip 4 includes an inner wall 28, an outer wall 30, and a crown 32connecting inner wall 28 and outer wall 30. In examples, welds atlocations 34 and 36, and optionally at 38, 40 and 42, connect burner tip4 to external conduit 10 and second internal conduit 14, usingconventional weld materials to weld together similar base metal parts,such as carbon steel, stainless steel, or titanium.

Selection of burner tip material and type of connections between theburner tip walls and conduits forming the burner body may significantlyincrease the operating life of submerged combustion burners used to meltmaterials in an SCM. More particularly, at least one of the corrosionand/or fatigue resistance of the outer wall of the burner tip is greaterthan material comprising the external conduit under conditionsexperienced during submerged combustion melting of materials.Additionally, the surfaces of the burner (including the burner tip orburner body) may be further processed after manufacture so as toincrease performance and reduce materials imperfections so as to improveresistance of these components to fatigue.

Burner tips may be manufactured of noble metals or other exoticcorrosion and/or fatigue-resistant materials, such as platinum (Pt),ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os),iridium (Ir), and gold (Au); alloys of two or more noble metals; andalloys of one or more noble metals with a base metal. In certainexamples the burner tip may be a platinum/rhodium alloy attached to thebase metals comprising the burner body using a variety of techniques,such as brazing, flanged fittings, interference fittings, frictionwelding, threaded fittings, and the like, as further described hereinwith regard to specific examples. Threaded connections may eliminate theneed for third party forgings and expensive welding or brazingprocesses—considerably improving system delivery time and overall cost.It will be understood, however, that the use of third party forgings,welding, and brazing are not ruled out for burners described herein, andmay actually be preferable in certain situations. Such connections aredescribed in the examples below.

When in alloyed form, alloys of two or more noble metals may have anyrange of noble metals. For example, alloys of two noble metals may havea range of about 0.01 to about 99.99 percent of a first noble metal and99.99 to 0.01 percent of a second noble metal. Any and all ranges inbetween 0 and 99.99 percent first noble metal and 99.99 and 0 percentsecond noble metal are considered within the present disclosure,including 0 to about 99 percent of first noble metal; 0 to about 98percent; 0 to about 97 percent; 0 to about 96; 0 to about 95; 0 to about90; 0 to about 80; 0 to about 75; 0 to about 70; 0 to about 65; 0 toabout 60; 0 to about 55; 0 to about 50; 0 to about 45, 0 to about 40; 0to about 35; 0 to about 30; 0 to about 25; 0 to about 20; 0 to about 19;0 to about 18; 0 to about 17; 0 to about 16; 0 to about 15; 0 to about14; 0 to about 13; 0 to about 12; 0 to about 11; 0 to about 10; 0 toabout 9; 0 to about 8; 0 to about 7; 0 to about 6; 0 to about 5; 0 toabout 4; 0 to about 3; 0 to about 2; 0 to about 1; and 0 to about 0.5percent of a first noble metal; with the balance comprising a secondnoble metal, or consisting essentially of a second noble metal (forexample with one or more base metals present at no more than about 10percent, or no more than about 9 percent base metal, or no more thanabout 8, or about 7, or about 6, or about 5, or about 4, or about 3, orabout 2, or no more than about 1 percent base metal).

Certain noble metal alloy examples include three or more noble metals,the percentages of each individual noble metal may range from equalamounts of all noble metals in the composition (about 33.33 percent ofeach), to compositions comprising, or consisting essentially of, 0.01percent of a first noble metal, 0.01 percent of a second noble metal,and 99.98 percent of a third noble metal. Any and all ranges in betweenabout 33.33 percent of each, and 0.01 percent of a first noble metal,0.01 percent of a second noble metal, and 99.98 percent of a third noblemetal, are considered within the present disclosure.

The choice of a particular material is dictated among other parametersby the chemistry, pressure, and temperature of fuel and oxidant used andtype of glass matrix to be produced. The skilled artisan, havingknowledge of the particular application, pressures, temperatures, andavailable materials, will be able design the most cost effective, safe,and operable burners for each particular application without undueexperimentation.

Various metals and metal alloys may display both corrosion resistanceand fatigue resistant resistance. These two terms are used herein referto two different failure mechanisms (corrosion and fatigue) that mayoccur simultaneously, and it is theorized that these failure mechanismsmay actually influence each other in profound ways. As such, the presentapplication utilizes a term that may be used to describe these dualinfluences, denoted “cortigue” or “cortigue resistance.” These termsrefer to a burner tip material that will have a satisfactory servicelife of at least 12 months under conditions existing in a continuouslyoperating SCM adjacent to the burner tip. As used herein the SCM maycomprise a floor, a roof, and a sidewall structure connecting the floorand roof defining an internal space, at least a portion of the internalspace comprising a melting zone, and one or more combustion burners ineither the floor, the roof, the sidewall structure, or any two or moreof these, producing combustion gases and configured to emit thecombustion gases from a position under a level of, and positioned totransfer heat to and produce, a turbulent molten mass of glasscontaining bubbles in the melting zone. An example of an SCM system isdepicted below in FIG. 16.

Certain examples may comprise a burner tip insert shaped substantiallythe same as but smaller than the burner tip and positioned in aninternal space defined by the burner tip, the insert configured so thata cooling fluid may pass between internal surfaces of the burner tip andan external surface of the insert. In these examples a first or distalend of the first internal conduit would be attached to the insert. Incertain examples, the inner and outer walls of the burner tip body mayextend beyond the first end of the first internal conduit, at leastpartially defining a mixing region for oxidant and fuel.

Conduits of burner bodies and associated components (such as spacers andsupports between conduits, but not burner tips) used in SC burners, SCMsand processes of the present disclosure may be comprised of metal,ceramic, ceramic-lined metal, or combination thereof. Suitable metalsinclude carbon steels, stainless steels, for example, but not limitedto, 306 and 316 steel, as well as titanium alloys, aluminum alloys, andthe like. High-strength materials like C-110 and C-125 metallurgies thatare qualified under standards set by NACE International of Houston,Tex., may be employed for burner body components. Use of high strengthsteel and other high strength materials may significantly reduce theconduit wall thickness required, reducing weight of the burners.

The melter geometry and operating temperature, burner and burner tipgeometry, and type of glass to be produced, may dictate the choice of aparticular material, among other parameters.

In certain SCMs, one or more burners in the SCM and/or flow channel(s)downstream thereof may be adjustable with respect to direction of flowof the combustion products. Adjustment may be via automatic,semi-automatic, or manual control. Certain system examples may comprisea burner mount that mounts the burner in the wall structure, roof, orfloor of the SCM and/or flow channel comprising a refractory, orrefractory-lined ball joint. Other burner mounts may comprise railsmounted in slots in the wall or roof. In yet other examples the burnersmay be mounted outside of the melter or channel, on supports that allowadjustment of the combustion products flow direction. Useable supportsinclude those comprising ball joints, cradles, rails, and the like.

Certain SCMs and process examples of this disclosure may be controlledby one or more controllers. For example, burner combustion (flame)temperature may be controlled by monitoring one or more parametersselected from velocity of the fuel, velocity of the primary oxidant,mass and/or volume flow rate of the fuel, mass and/or volume flow rateof the primary oxidant, energy content of the fuel, temperature of thefuel as it enters the burner, temperature of the primary oxidant as itenters the burner, temperature of the effluent, pressure of the primaryoxidant entering the burner, humidity of the oxidant, burner geometry,combustion ratio, and combinations thereof. Certain SCMs and processesof this disclosure may also measure and/or monitor feed rate of batch orother feed materials, such as glass batch, cullet, mat or wound rovingand treatment compositions, mass of feed, and use these measurements forcontrol purposes. Exemplary systems and methods of the disclosure maycomprise a combustion controller which receives one or more inputparameters selected from velocity of the fuel, velocity of oxidant, massand/or volume flow rate of the fuel, mass and/or volume flow rate ofoxidant, energy content of the fuel, temperature of the fuel as itenters the burner, temperature of the oxidant as it enters the burner,pressure of the oxidant entering the burner, humidity of the oxidant,burner geometry, oxidation ratio, temperature of the burner combustionproducts, temperature of melt, composition of bubbles and/or foam, andcombinations thereof, and may employ a control algorithm to controlcombustion temperature, treatment composition flow rate or composition,based on one or more of these input parameters.

In the burners described in the below examples, the burner tip may bejoined to burner body using flanges. When joined in this way, somedesign considerations include the thickness of the flange, the width ofthe flange, and the shape of the area surrounding the junction as thislocation is typically cooled with a coolant fluid and pressure dropneeds to be minimized. In addition, when using flanges, gasket materialis selected to ensure sealing and the ability to expose the flange to anoxygen or oxygen-enriched environment. In addition, or in certainalternative examples, plastically deformable features may be positionedon one or more of the flange faces to enable joint sealing.

In other examples, brazing compounds and methods may be used to attachburner tip to burner body. Brazing allows the joining of dissimilarmetals and also allows for repairs to be made by removing the brazematerial. For these examples to be successful, the mating surfaces mustbe parallel or substantially so, and of sufficient overlap to ensurethat the brazing material may properly flow between the portions of theburner tip and burner body being joined. This may be achieved in certainexamples using a flange at right angles to both the burner tip walls 28,30 (depicted in FIG. 1 and described in more detail below), and theconduits forming burner body. In other examples brazing may besuccessfully achieved by making the burner tip walls 28, 30 and conduits14, 10 overlap with sufficient gaps to allow brazing material to enterthe gaps.

Braze compounds, sometimes referred to as braze alloys, to be useful incertain examples, must have liquidus and solidus temperatures above thehighest temperature of the burner tip. The highest temperature of theburner tip will be a temperature equal to the melt temperature existingin the SCM reduced by the flow of coolant through the burner tip, aswell as by the flow of combustion gases through the burner tip. Thehighest temperature of the burner tip during normal operating conditionsdepends on the type of matrix being melted, which makes the selection ofbraze alloy not a simple matter. For Na—Ca—Si soda-lime window glass(Glass 1), typical melt temperature may range from about 1275° C. toabout 1330° C.; for Al—Ca—Si E glass having low sodium and zero boron(Glass 2), the melt temperature may range from about 1395° C. to about1450° C.; for B—Al—Si glass, zero sodium, zero potassium, high Si (Glass3), the melt temperature may be about 1625° C.; and for B—Al—Ca—Si Eglass used for reinforcement fiber (Glass 4), the melt temperature maybeabout 1385° C. This information was taken from Rue, D., “EnergyEfficient Glass Melting—The Next Generation Metter”, p. 63, GTI ProjectNumber 20621, March, 2008 (U.S. Dept. of Energy). Based on thesetemperatures, and assuming a drop in burner tip temperature of 300° C.due to coolant and gas flow through the burner tip, Table 1 lists thepossible braze alloys that may be used.

TABLE 1 Braze Alloys Glass Melt Solidus Glass Type T, (° C.) PossibleBraze Alloys T, (° C.) 1 1275-1330 Pt 1769 Pd 1555 Ti 1670 Au/Pd (92/8,PALORO (BAU-8)) 1200 Ni/Pd (40/60, PALNI) 1238 Pd/Co (65/35, PALCOBPD-1) 1219 Pd/Ni/Au (34/36/30, PALNIRO 4 1135 (AMS-4785)) Cu 1083 Au1064 2 1395-1450 Pt 1769 Pd 1555 Ti 1670 Au/Pd (92/8, PALORO (BAU-8))1200 Ni/Pd (40/60, PALNI) 1238 Pd/Co (65/35, PALCO BPD-1) 1219 3 1625 Pt1769 Ti 1670 4 1385 Pt 1769 Pd 1555 Ti 1670 Au/Pd (92/8, PALORO (BAU-8))1200 Ni/Pd (40/60, PALNI) 1238 Pd/Co (65/35, PALCO BPD-1) 1219 Pd/Ni/Au(34/36/30 PALNIRO 4 1135 (AMS-4785))

In yet other examples, burner tip walls and conduit 14, 10 may bethreaded together, in certain examples accompanied by a sealant surfaceof flange upon which sealants, gaskets or O-rings may be present.Threaded joints may be straight or tapered such as NPT. In certainthreaded examples the sealing surfaces of burner tip walls 28, 30 may bemalleable enough compared to conduits 14, 10 to deform and form theirown seals, without sealants, gaskets, or O-rings.

In still other examples, burner tip walls 28, 30 may be interference orpress fit to their respective conduit 14, 10 of burner body 6. In theseexamples, the walls and/or conduits are machined to sufficiently closetolerances to enable deformation of one or both surfaces as the twoparts are forcefully joined together.

In yet other examples, burner tip walls 28, 30 may be friction weldedtogether. In these examples, either the burner tip walls or burner bodyconduits, or both, may be spun and forced into contact until sufficienttemperature is generated by friction to melt a portion of either or bothmaterials, welding walls 28, 30 to conduits 14, 10, respectively. Theseexamples may include one or more additional metals serving as anintermediate between walls 28, 30 and conduits 14, 10 to facilitatefriction welding.

Specific non-limiting burner, burner tip, SCM and process examples inaccordance with the present disclosure will now be presented inconjunction with FIGS. 1-11. The same or similar numerals are used forthe same or similar features in the various figures. In the viewsillustrated in FIGS. 1-8, it will be understood in each case that thefigures are schematic in nature, and certain conventional features arenot illustrated in order to illustrate more clearly the key features ofeach example.

Referring now again to the figures, FIGS. 2-11 are schematiclongitudinal cross-sectional views of non-limiting examples offluid-cooled portions of various examples of SC burners in accordancewith the present disclosure, while FIGS. 2A, 6A, 7A, 8A, and 11A aredetailed cross-sectional views of various burner features describedherein. Embodiment 100 illustrated schematically in FIG. 2 includes aPt/Rh or other corrosion and fatigue resistant inner flange portion 50mated with a base metal inner flange portion 52. Flange portions 50, 52serve to connect inner wall 28 of the burner tip to second internalconduit 14. Also illustrated are Pt/Rh or other corrosion and fatigueresistant outer flange portion 54 mated with a base metal outer flangeportion 56. Flange portions 54, 56 serve to connect outer wall 30 of theburner tip to external conduit 10. Bolting is not illustrated forclarity, but it is understood that flange portions 50, 52 are boltedtogether, as are flange portions 54, 56. Bolting may be of thethreaded-bolt-and-nut type, or simply a threaded bolt that passescompletely through one flange portion and partially or completelythrough the mating flange portion. Bolting of the latter type isillustrated schematically in embodiment 200 of FIG. 4, illustratingbolts 62, 64, 66, and 68.

The dimensions of thickness “T” and width “W” of the flange connectionformed by flange portions 50, 52 are illustrated schematically in FIG.2A, as well as a shape feature, “5”, in dashed lines, indicating thatflange portion 50, 52 may have some other shape to minimize pressuredrop of coolant fluid through the first and second annuli, discussedherein. Note that “W” must be a value that allows a gap between theflange formed by flange portions 50, 52 and the first internal conduit12 depicted in FIG. 1 (not shown in FIG. 2) to allow warmed coolantfluid to flow out of the fluid-cooled portion of the burner. Dependingon the inner diameter of first internal conduit 12 in the location offlange portions 50, 52, “W” may range from 1 or more centimeters, incertain examples up to 30 centimeters or more. “T” may range from about1 to about 10 centimeters, or from about 1 to about 5 centimeters. “S”may be rounded, ovoid, or angled, chamfered, beveled, and the like.

FIG. 3 is a perspective view of the burner tip of embodiment 100,illustrating schematically the inclusion of deformable features 58, 60on the faces of flange portions 50, 54. In the embodiment illustrated inFIG. 3, deformable features 58, 60 are raised linear areas of Pt/Rh orother corrosion/fatigue resistant material, but the format of thedeformable areas may be any format that will deform the areas to form aseal, such as a plurality of discrete circular areas (“dots”), or dashedareas. Another embodiment, not illustrated, is to provide machined ormolded non-deformable areas or regions on the mating faces of base metalflange portions 52, 56 (FIG. 2) and allow these non-deformable featuresto deform mating regions of corrosion/fatigue resistant flange portions50, 54, it being understood that the hardness and/or ductility of thebase metal are generally greater than the hardness and/or ductility ofthe corrosion/fatigue resistant material of the burner tip.

Careful selection of gasket material is a feature of embodiment 200illustrated in FIG. 4, which does not employ deformable features in theflange faces. In these examples, the gasket material used is resistantto oxygen attack, the required resistance level being greater as thepercentage of oxygen in the oxidant stream increases. Suitable metallicgasket materials depend on the temperature, oxygen concentration, andexpected life, but may include INCONEL (an alloy comprising 77 percentNi, 15 percent Cr and 7 percent Fe) and titanium. Silica fabrics andsilica tapes, such as those known under the trade designation MAXSIL(McAllister Mills, Inc., Independence, Va.), may be used.

FIG. 5 illustrates schematically embodiment 300 employing the same ordifferent braze materials 70 and 72 between flange portions 54, 56 and50, 52, respectively. The braze materials may be independently selectedfrom any metallic braze materials having a solidus temperature at least10° C., preferably at least 20° C. greater than the burner tiptemperature, cooled by flowing coolant and flowing combustion gases,oxidant and/or fuel. Some non-limiting examples are provided in Table 1herein. In certain examples it may not be necessary that the brazematerial fill the entire width “W” of the flange joint or joints,however, those examples having 100 percent fill are exemplary examples.

FIG. 6 illustrates schematically embodiment 400, an alternative whereinthe same or different braze materials 74, 76, 78, and 80 are used injoints that are substantially parallel to the conduits of the burner andwalls of the burner tip. Braze materials 74, 76, 78, and 80 may beindependently selected from any metallic braze materials having asolidus temperature at least 10° C., preferably at least 20° C. greaterthan the burner tip temperature, cooled by flowing coolant and flowingcombustion gases, oxidant and/or fuel. Some non-limiting examples areprovided in Table 1 herein. In certain examples it may not be necessarythat the braze material fill the entire overlapping area of the joinedparts, however, those examples having 100 percent fill of theoverlapping areas are exemplary examples. A more detailed view of thebraze area 74 is illustrated schematically in FIG. 6A. In theseexamples, the corrosion/fatigue resistant material of burner tip walls28, 30 do not deform substantially, although they may deform slightly.

FIG. 7 illustrates schematically embodiment 500, an alternative whereinthe same or different threaded joints 82, 84, 86, and 88 may be present.FIG. 7A illustrates a detailed view of threaded joint 82, a straightthread. Tapered threads may also be employed. As mentioned herein,threaded joint may utilize sealants, gaskets, O-rings, and the like, ormay simply utilize deformable threads. Certain threaded examples may usea combination of two or more of these sealing techniques.

FIG. 8 illustrates yet another embodiment 600, embodiment 600 featuringinterference fittings 90, 92, 94, and 96 between inner and outer walls28, 30 of the corrosion/fatigue resistant burner tip, and conduits 10and 14 of the base material burner body. FIG. 8A is a detailed schematicillustration of interference fit joint 90, illustrating in a slightlyexaggerated manner the deformation of out wall 30.

FIG. 9 illustrates schematically yet another embodiment 630, featuringinner and outer threaded rings 29, 31, O-rings 33, 35, and weld, solder,or braze areas 37, 39. Arrows on the left portion of FIG. 9 illustratedschematically repositioning of conduit 12 so that insert 26 will fitbetween threaded rings 29, 31 upon assembly and disassembly. Twopositioning pins 27 are illustrated (more or less than two may be used),which function to maintain a gap between insert 26 and crown 32 forcoolant flow. In embodiment 630, burner tip inner and outer walls 28,30, and crown 32 may be a single noble metal piece, or may be separatepieces welded, soldered, or brazed together. Issues of possiblecrossthreading of noble metal threads of inner and outer walls 28, 30 ofthe burner tip to noble metal or non-noble metal threads of rings 29, 31may disfavor this design, as well as the need to reposition conduit 12.In one variation, threads may instead be press-fit locking dogconnections.

FIG. 10 illustrates schematically yet another embodiment 650 featuringlower and upper flange connectors 41, 43, which may be fastened togetherusing one or more clips 45. O-rings, gaskets, or other seals 91, 93,with or without one or more grooves in flange faces, may be used ifnecessary. Lower flange connector 41 may be welded, soldered, or brazedto conduit 10 at 25, and to conduit 14 at 38. Upper flange connector 43may be welded, soldered, or brazed to burner tip outer wall 30 at weldor braze area 34, and to burner tip inner wall 28 at weld or braze area36. As with embodiment 630, embodiment 650 may be disfavored due to theneed to reposition conduit 12 as illustrated by arrows (12 a indicatespossible new position, and 12 b original position), and possible need toremove portions of insert 26, as indicated at 49, so that insert 26 willfit between flanged areas during assembly and disassembly.

FIG. 11 illustrates schematically yet another embodiment 680 featuringlocking dog or other type of shaped connectors 57, 59 (such as ribs,knurls, scallops, and the like) used to connect a lower area 53 ofburner tip outer wall 30 to a shaped “grip ring” 51, as perhaps moreevident in the detail of FIG. 11A. This type of connection, or adifferent type, may be used to connect a lower area of burner tip innerwall 28 to another shaped grip ring 63. Shaped grip ring 51 may bewelded, soldered, or brazed to conduit 10 at area 55, and shaped gripring 63 may be welded, soldered, or brazed to conduit 14 at area 61. Toeffect coolant seals, areas 65 maybe welded, soldered, or brazed usingappropriate materials for the service and conduit materials. As withexamples 630, 650, embodiment 680 may require a slight repositioning ofconduit 12 as illustrated by arrows (12 a indicates possible newposition, and 12 b original position), however there should be less needto remove portions of insert 26 so that insert 26 will fit betweenflanged areas during assembly and disassembly, as insert 26 and conduit12 need only clear grip rings 51, 63. Burner tip walls 28, 30, and crown32 may comprise noble metal. Grip rings 51, 63 may each comprise a basemetal with noble metal rolled thereon to form shaped connectors 57.

Those of skill in the art will appreciate that examples within thepresent disclosure may include a combination of the joining methodsdescribed herein, for example, in embodiment 300 illustratedschematically in FIG. 5, braze material 72 may be replaced withdeformable features forming a seal, as described in relation toembodiment 100 illustrated schematically in FIGS. 2-3. Anotherembodiment may include, for example, interference fittings 92, 94between second internal conduit 14 and inner wall 28 as illustratedschematically in FIG. 8, and brazed joints 74, 80, as illustratedschematically in FIG. 6. Yet other examples may include flange jointsformed by flange portions 50, 52 and interference fittings 90, 96. Othervarious combinations of the techniques of joining burner tips and burnerbodies of dissimilar metals disclosed herein are deemed within thepresent disclosure.

Those of skill in the art will also appreciate that outside of theburners described herein the warmed heat transfer fluid would be cooledso that it may be reused. As may also be appreciated, burner examplesdescribed herein define a mixing region 150 (FIG. 8) where fuel “F” andoxidant “0” mix, the mixing region 150 being partially formed by thethrough passage through burner tip, defined by burner tip inner wall 28.In certain examples, fuel emanates from the distal end of centralconduit 15 (FIG. 1), and oxidant traverses through a third annulus 19between central conduit 15 and second internal conduit 14, however, asmentioned herein, these flows could be changed so that fuel traversesthird annulus 19 and oxidant traverses through central conduit 15.

The thickness of crown 32 and inner and outer walls 28, 30 in thevarious examples illustrated herein is not critical, and need not be thesame for every region of the crown and walls. Suitable thicknesses mayrange from about 0.1 cm to about 1 cm, or larger. It is theorized theremay be a balance between corrosion and fatigue resistance, andthickness, with the thickness requirement generally being increased ifthe “cortigue” resistance of the crown and/or wall material is reduced.Thicker crowns and walls, or thicker regions of crowns and walls, willgenerally be stronger and exhibit more fatigue resistance, but may bemore difficult to install, for example if deformable interferencefittings are to be employed.

Regardless of the types of structure used to join the burner tip to theburner body, several examples of which are described above, it has beendiscovered that the burners or portions thereof may be subjected to oneor more post-manufacturing processes that may reduce fatigue points onthose structures or otherwise improve the microstructure thereof. Thesepost-manufacturing processes may be performed before or after theportions of the burner are joined. In that case, the processes may beperformed on either or both of the burner tip or the burner body, eitherbefore or after these two elements are joined at flanges, welds, orother structures.

FIGS. 12A and 12B are a view and an enlarged view of a burner surface200 and are described simultaneously. FIG. 12A, depicts a burner surfaceat approximately 20× magnification, while FIG. 12B depicts a burnersurface at 200× magnification, to further illustrate the characteristicsdescribed herein. Common fatigue points are evident in FIGS. 12A and12B, where machining lines and post-machining surface scratches maybecome mechanical or thermal fatigue crack initiation sites duringservice life of the burner. A plurality of machining lines 202 aredepicted, substantially parallel to the machining line arrow 204.Additionally, a plurality of surface scratches 206 are depictedsubstantially parallel to surface scratch line arrow 208. Both machininglines 202 and surface scratches 206 may propagate into fatigue cracks.For example, fatigue crack 210 is depicted emanating from machining line202 a, while fatigue crack 212 is depicted emanating from surfacescratch 206 a. Although the measurements may vary from burner to burner,surface scratches and common machined component surface finish featuresare typically about 10 to about 100 microns in depth, and vary dependingon machining technology and machine settings. Within the burner, stressexists not only through the material thickness, but also at the burner'ssurface. A rough surface condition results in stress risers at anydiscontinuity, those stress risers result in decreased time to onset offatigue cracks. Once such fatigue cracks 210, 212 are initiated, theydeepen and lengthen due to the burner's volatile thermal conditions andresulting stress cycling.

It has been discovered, however, that polishing of the burner aftermanufacture may mitigate the onset of fatigue initiation. The polishingdecreases the microscopic surface variation, and thus delays the onsetof fatigue. The portions of the burner that may benefit from polishingto remove surface discontinuities include any areas of the burner thatare exposed to the volatile thermal conditions in the SCM. As such,polishing of the toroidal burner tip may significantly improveperformance. However, polishing of the burner body, especially the areasthereof disposed proximate the burner tip or the connection points tothe burner tip, may also improve performance. In examples, a preferredsurface finish is less than about 1.0 micron or less than about 0.5micron. More specifically, the surface finish may be between about 1.0to about 0.1 micron. The polishing may have a circumferential ormultiple random orientations of the microscopic as-finished surfacetexture. However, any amount of finishing which reduces surfaceroughness from the as-machined or as-scratched condition is beneficial,whether circumferential or randomly oriented.

The polishing processes reduce the surface roughness of the burner (or aportion thereof) from a first, higher surface roughness, to a second,lower surface roughness. It may be advantageous to measure the firstsurface roughness across an entire area of the burner, or discreteportions thereof (either randomly or specifically). This enables adetermination of an average first surface roughness. As the polishingprocess proceeds, the roughness of the same surface may be measured(again, across the entire area of the burner, or portions thereof).Re-measuring of the surface roughness may determine an average secondsurface roughness. If the average second surface roughness is still notdesirable, polishing of the burner may continue until the desiredsurface roughness is achieved. The amount of polish may be measuredbased on surface roughness measurements, surface features measurements,other measurements, or combinations thereof. One or more polishingoperations (separated by measuring operations to determine surfacefinish) may reduce the average surface roughness such that apost-polishing surface roughness is about 5% of the pre-polishingsurface roughness. In other examples, polishing operations may reducethe average surface roughness such that a post-polishing surfaceroughness is about 1% of the pre-polishing surface roughness. Apost-polishing surface roughness about 0.1% of the pre-polishing surfaceroughness may also be desirable.

FIG. 13 depicts a method 300 of polishing a portion of a burner aftermanufacture. The method 300 begins with disposing a portion of an SCMburner in a vise in operation 302. Securing in a vise specifically isnot required. Instead, the portion to be polished must be generallyfixed in position such that it resists movement during polishingprocesses. In examples, the portion of the burner secured is thetoroidal tip, although other portions of the burner, e.g., the burnerbody, could be secured for polishing purposes. Before polishing begins,the portion of the burner may be characterized as having an averagefirst surface roughness across an area of the burner. The area may bethe entire exposed surface of the portion of the burner to be polished.In other examples, the area may be a defined area contained within aboundary that may be measured before and after polishing to quantifyresults of polishing. In operation 304, the portion of the burner ispolished to an average second surface roughness across the area of theportion of the burner. Of course, the average second surface roughnessis less than the average first surface roughness. Example heights ofsurface features before and after polishing are described above. Whencomparing the two surface roughnesses, the differences may besignificant as described above. It is often advantageous to performoperation 304 in a random pattern about the surface to be polished.Circumferential polishing is also contemplated.

FIGS. 14A and 14B depict microstructures of cast precious metal samples400, 400′ before and after hot isostatic pressing processes,respectively. Post-processing of a burner or a part thereof (e.g., aburner body or a burner tip), as part of the manufacturing processimproves the microstructure of the processed part by minimizingmorphological differences through the part and eliminating defects ofthe exposed part, providing operational service life or mechanicalproperty advantage. Post-manufacturing processing (as used herein“post-processing”) includes heat treatments, hot-isostatic pressing(HIP), and similar timed temperature and/or pressure treatments. Theseprocesses, described in the context of FIGS. 14A, 14B, and 15, may beperformed before or after the polishing processes described above.Alternatively, the polishing processes need not be performed at all fora part of a burner to benefit from the heat treatment process describedherein.

By subjecting the burner part to post-processing, part life is extendedby manipulating the size, aspect ratio, range, and/or orientation of thegrains, as well as by eliminating voids, chemical micro-segregation, andother defects within the microstructure of the processed part. Thishelps the part withstand the volatile thermal environment and fatiguefailures which may onset therein. In an un-processed part, defects andgrains which are columnar (especially when columnar grains are alignedperpendicular to stress) enable rapid crack initiation and propagationwhile experiencing thermal and/or mechanical loads during service.Therefore, service life and mechanical properties such as ductility andstrength are improved (and therefore are more accurately tailored) tothe specific condition of the part during service. Another advantage isthat post-processing of the part does not significantly change itsgeometry, therefore little or no additional machining is required tomeet dimensional specifications.

In welded areas, morphological differences between the weld metal andthe base metal provides higher probability for failure at the fusionline or heat affected zone, therefore post-processing any parts of theburner that have been welded minimizes or eliminates these differences,which greatly reduces the chances for failure, and improves theintegrity of that part, therefore extending service life. Thepost-processing technologies described herein may be applied to metallicmaterials such as superalloy, precious, and other non-precious metalsystems. The technology may be further applied to most any formingtechnologies including cast, wrought, forged, pressed, rolled, directmetal laser sintered, or other methods which generate less-than-desiredmorphology or non-uniformity within the burner. This also applies toboth the raw part and within the burner around any repaired, welded,jointed, or otherwise discontinuous morphology as a result of the meansused to manufacture the burner. In the context of SCM burners, thetechnology is particularly desirable since those burners are typicallyformed from cast precious metal parts. Cast precious metal displaysuperior ductility and other properties that provide relatively highthermal shock resistance. Such precious metals also display risk ofinferior attributes due to the localized non-uniformities (such ascasting gates) required to form a cast burner.

Other advantages of post-processing are that the burner may be cast,weld-repaired, welded, or otherwise formed in ways that result inundesirable non-uniform or unintended voids or defects in themicrostructure. Such burners, and especially the areas of the burnerthat have been welded, may be post-processed to eliminate such defectsand still provide advantageous microstructure for improved partperformance. Types of post-processing include heat treatments thatapproach a melting temperature of the metal, or at least at acombination of sufficient temperatures and times to promote nucleation,recrystallization, and grain growth-in. By utilizing these treatments,the microstructure is managed to a preferred condition. In an example,the post processing is hot isostatic pressing (HIP) that provides boththe desired microstructure and also causes any defects or voids in themicrostructure to be closed while grains recrystallize. This, inessence, mends any defects, including those caused by welding. Any suchmended defects are one less potential failure site of the componentduring its life in the volatile thermal and mechanical loadingenvironment of an SCM system.

FIG. 14A depicts a microstructure of a metal sample 400, prior to anypost-processing. In this as-cast condition, the sample 400 displaysunfavorable elongated grains 402 protruding inwards from the exteriorsurface, and also exhibits a high concentration of voids 404. In FIG.14B, a post-processed sample 400′ is depicted. The sample 400′ has beensubjected to HIP, which results in the grains 402′ being no longerelongated inwards from the outer surface. Virtually all voids have beeneliminated.

Table 2 depicts a range of HIP parameters, as well as parameters thatproduced particularly desirable results (identified as Example 1). InExample 1, a burner formed by a precious metal having a combination ofabout 80% Pt and about 20% Rh was utilized and subjected to HIPprocessing. Burners manufactured from combinations of Pt and Rh areparticularly desirable because such combinations maintain a single phaseregardless of temperature. This single phase performance may apply toany percentage combination of Pt and Rh (e.g., 0%-100% Pt through100%-0% Rh). For example, burners manufactured from about 70% Pt andabout 30% Rh, as well as burners manufactured from about 90% Pt andabout 10% Rh, are expected to perform similarly. Other precious metalshaving different percentages of Pt and Rh are contemplated for burners.

TABLE 2 HIP parameters for burner post-processing Parameter RangeExample 1 Temperature 2200 to 3000° F. 2600° F. Time 100 to 1000 minutes365 minutes Pressure 20,000 to 50,000 psi 30,000 psi

It has also been discovered that multiple post-processing cycles (e.g.,HIP cycles) may be performed on a burner to achieve more desirableresults. Table 3, below, depicts example pressures, temperature, andtimes for HIP processing of test parts that have been subjected to bothlaser welding and gar tungsten arc welding (GTAW), for multiple HIPcycles. Laser welding and GTAW produce different defects to themicrostructure adjacent the weld. For example, laser welding causes asignificant number of voids directly adjacent a very fine weld area,whereas GTAW creates a significant number of elongated grains over afairly large area, with a large number of voids disposed just outsidethe area of grains. Removing these defects through HIP processing helpsincrease the life of the part. Prior to each HIP cycle, nondestructivedefect detection techniques (such as dye penetrant inspection andradiography) may be performed to identify any defects for potential weldrepair. This multi-step process brings additional mending to defects inthe microstructure. Care should be taken so as not to cause overly largegrains (and direct paths through grain boundaries) for cracks topropagate.

TABLE 3 Example HIP parameters Thickness No. Sample [in] Pressure [psi]T [° F.] t [min] 1 As Cast 0.06 n/a n/a n/a 2 As Cast 0.09 n/a n/a n/a 3HIP-1 0.06 30,000 +/− 250 2417 +/− 25 365 +/− 15 2417 4 HIP-1 0.0930,000 +/− 250 2417 +/− 25 365 +/− 15 2417 5 HIP-1 0.06 29,750 +/− 2502600 +/− 25 365 +/− 15 2600 6 HIP-1 0.09 29,750 +/− 250 2600 +/− 25 365+/− 15 2600 7 HIP-2 0.06 30,000 +/− 250 2417 +/− 25 365 +/− 15 2417 8HIP-2 0.09 30,000 +/− 250 2417 +/− 25 365 +/− 15 2417 9 HIP-2 0.0629,750 +/− 250 2600 +/− 25 365 +/− 15 2600 10 HIP-2 0.09 29,750 +/− 2502600 +/− 25 365 +/− 15 2600

In the above Table 3, Samples 1 and 2 were as-cast test pieces havingtwo different thicknesses that were not subjected to any HIP processing.Samples 3-5 are test parts having thicknesses as indicated and subjectedto HIP processing with under the parameters indicated. All of Samples3-5 were welded with both laser and GTAW welds. After one cycle of HIPprocessing, testing was performed to observe the remaining defects inthe part. Proximate the laser weld, a significant number of the voidshad been removed from the part and some voids had combined into single,rounder voids. This indicated that further processing would likelycompletely remove these rounder voids from the material. Proximate theGTAW welds, elongated grains had become more equiaxed and regular inshape, and very few voids were present. After subjecting the samples toa second cycle of HIP processing (Samples 7-10), nearly all voids wereremoved from the samples proximate the laser welds, while the grainsproximate the GTAW weld were further equiaxed and the voids eliminated.

FIG. 15 depicts a method 500 of hot isostatic processing a part aftermanufacture. The method 500 begins with operation 502, where a part isdisposed within a pressure vessel. The burner part may be the burnerbody, the toroidal burner tip, or the burner itself (e.g., the combinedburner tip and burner body). The part has a first microstructure definedby, among other characteristics, a first number of voids. The firstmicrostructure may also be defined by elongated grains or otherstructures. Once the part is disposed in the pressure vessel, the vesselis sealed and filled with an isostatic gas such as argon or anotherinert gas, as in operation 504. In operation 506, the vessel ispressurized and in operation 508, the vessel is heated. These operationsmay occur substantially simultaneously. Example pressures may be betweenabout 20,000 psi and about 50,000 psi; between about 25,000 psi andabout 40,000 psi; and about 30,000 psi. Examples temperatures may bebetween about 2200 degrees F. to about 3000 degrees F.; between about2450 degrees F. to about 2750 degrees F.; and about 2600 degrees F. Thepart may be held at the elevated temperature and pressure for a timesufficient to produce a second microstructure in the burner part. Thesecond microstructure is defined by a second number of voids that isless than the first number of voids. As with the first microstructure,the second microstructure may also be characterized by elongated grainsor other structures.

In testing performed on a burner part prior to HIP processing, it hasbeen determined that the size and number of voids are significant.Testing has revealed that, prior to processing, voids can be as much as500 microns in diameter. Void fraction in the first microstructure(again, prior to processing) can be as high as 20% or higher in welds.After HIP processing, void fraction can be reduced to significantly lessthan 1% (effectively 0%). Any remaining voids, however infrequent, maybe much less than 5 microns in diameter. Regarding microstructure, thefirst microstructure can be dictated at least in part by the thicknessand shape of the part in the region of interest, and the manufacturingmethods to form the part. In the example above in FIG. 14A, the firstmicrostructure reveals highly columnar grains before HIP. After HIP, thesecond microstructure is significantly more equiaxed and regular inshape. Specific analytical tools are known to quantify grain size,aspect ratio, size distribution, etc., and such tools would be known toa person of skill in the art. In general, the goal after HIP is toproduce a microstructure that is more equiaxed and regular, with fewervoids, grains having more rounded edges, etc. As such, themicrostructure is more normalized and is not simply heterogeneous withvoids and defects. A more normalized microstructure displays advantagesover a microstructure having elongated grains, which are unstable andhave large driving force due their geometry to re-form at hightemperatures. As such, elongated grains more easily form cracks, sincethe grain boundaries are highly aligned for cracks to propagate.Sufficient times to achieve the second microstructure may be betweenabout 100 minutes to about 1000 minutes; between about 200 minutes toabout 600 minutes; and about 365 minutes.

Once the appropriate amount of time has elapsed, the vessel isdepressurized and cooled. Thereafter, in operation 510, the burner partis removed from the vessel. As described above, the part may benon-destructively tested so as to identify a burner defect, operation512. In operation 514, defects may be weld-repaired. In operation 516,if desired, the part of the burner may be returned to the vessel andoperations 502-508 repeated.

FIG. 16 depicts a side sectional view of a melter system 600 that may beutilized in conjunction with the examples of the burners describedabove. The melter system 600 is a submerged combustion melter (SCM) andis described in more detail in U.S. Patent Application Publication No.2013/0283861, the disclosure of which is hereby incorporated byreference herein in its entirety. Melter apparatus or melt vessel 601 ofFIG. 6 includes a floor 602, a roof or ceiling 604, a feed end wall606A, a first portion of an exit end wall 606B, and a second portion ofthe exit end wall 606C. Each of the floor 602, the roof 604, and walls606A, 606B, and 606C comprise a metal shell 617 and a refractory panel609, some or all of which may be fluid-cooled. Exit end wall portion606C may form an angle with respect to a skimmer 618.

The melt vessel 601 may be fluid cooled by using a gaseous, liquid, orcombination thereof, heat transfer media. In certain examples, the wallmay have a refractory liner at least between the panels and the moltenglass. Certain systems may cool various components by directing a heattransfer fluid through those components. In certain examples, therefractory cooled-panels of the walls, the fluid-cooled skimmer, thefluid-cooled dam, the walls of the fluid-cooled transition channel, andthe burners may be cooled by a heat transfer fluid selected from thegroup consisting of gaseous, liquid, or combinations of gaseous andliquid compositions that function or are capable of being modified tofunction as a heat transfer fluid. Different cooling fluids may be usedin the various components (e.g., wall portions of the melt vessel 601,the burners 612, etc.), or separate portions of the same coolingcomposition may be employed in all components. Gaseous heat transferfluids may be selected from air, including ambient air and treated air(for air treated to remove moisture), inert inorganic gases, such asnitrogen, argon, and helium, inert organic gases such as fluoro-,chloro- and chlorofluorocarbons, including perfluorinated versions, suchas tetrafluoromethane, and hexafluoroethane, and tetrafluoroethylene,and the like, and mixtures of inert gases with small portions ofnon-inert gases, such as hydrogen. Heat transfer liquids may be selectedfrom inert liquids, which may be organic, inorganic, or some combinationthereof, for example, salt solutions, glycol solutions, oils and thelike. Other possible heat transfer fluids include water, steam (ifcooler than the oxygen manifold temperature), carbon dioxide, ormixtures thereof with nitrogen. Heat transfer fluids may be compositionsincluding both gas and liquid phases, such as the higherchlorofluorocarbons.

The melt vessel 601 further includes an exhaust stack 608, and openings610 for submerged combustion burners 612, which create during operationa highly turbulent melt matrix indicated at 614. Examples of SCM burners612 are described above. Highly turbulent melt matrix 614 may have anuneven top surface 615 due to the nature of submerged combustion. Anaverage level 607 is illustrated with a dashed line. In certainexamples, burners 612 are positioned to emit combustion products intomolten matrix in the melting zone 614 in a fashion so that the gasespenetrate the melt generally perpendicularly to floor 602. In otherexamples, one or more burners 612 may emit combustion products into themelt at an angle to floor 602.

In an SCM, combustion gases emanate from burners 612 under the level ofa molten matrix. The burners 612 may be floor-mounted, wall-mounted, orin melter examples comprising more than one submerged combustion burner,any combination thereof (for example, two floor mounted burners and onewall mounted burner). These combustion gases may be substantiallygaseous mixtures of combusted fuel, any excess oxidant, and combustionproducts, such as oxides of carbon (such as carbon monoxide, carbondioxide), oxides of nitrogen, oxides of sulfur, and water. Combustionproducts may include liquids and solids, for example soot and unburnedliquid fuels.

At least some of the burners may be mounted below the melt vessel, andin certain examples the burners may be positioned in one or moreparallel rows substantially perpendicular to a longitudinal axis of themelt vessel. In certain examples, the number of burners in each row maybe proportional to width of the vessel. In certain examples the depth ofthe vessel may decrease as width of the vessel decreases. In certainother examples, an intermediate location may comprise a constant widthzone positioned between an expanding zone and a narrowing zone of thevessel, in accordance with U.S. Patent Application Publication No.2011/0308280, the disclosure of which is hereby incorporated byreference herein in its entirety.

Returning to FIG. 6, the initial raw material may be introduced intomelt vessel 601 on a batch, semi-continuous or continuous basis. In someexamples, a port 605 is arranged at end 606A of melt vessel 601 throughwhich the initial raw material is introduced by a feeder 634. In someexamples, a batch blanket 636 may form along wall 606A, as illustrated.Feed port 605 may be positioned above the average matrix melt level,indicated by dashed line 607. The amount of the initial raw materialintroduced into melt vessel 601 is generally a function of, for example,the capacity and operating conditions of melt vessel 601 as well as therate at which the molten material is removed from melt vessel 601.

The initial raw material may include any material suitable for forming amolten matrix, such as glass and/or inorganic non-metallic feedstockssuch as rock (basalt) and mineral wool (stone wool). With regard toglass matrices, specifically, limestone, glass, sand, soda ash, feldsparand mixtures thereof may be utilized. In one example, a glasscomposition for producing glass fibers is “E-glass,” which typicallyincludes 52-56% SiO₂, 12-16% Al₂O₃, 0-0.8% Fe₂O₃, 16-25% CaO, 0-6% MgO,0-10% B₂O₃, 0-2% Na₂O+K₂O, 0-1.5% TiO₂ and 0-1% F₂. Other glasscompositions may be used, such as those described in U.S. PublishedPatent Application No. 2008/0276652, the disclosure of which is herebyincorporated by reference herein in its entirety. The initial rawmaterial may be provided in any form such as, for example, relativelysmall particles.

As noted herein, submerged combustion burners may produce violentturbulence of the molten matrix and may result in a high degree ofmechanical energy (e.g., vibration V in FIG. 6) in the submergedcombustion melter that, without modification, is undesirably transferredto the conditioning channel. Vibration may be due to one or more impactsfrom sloshing of the molten matrix, pulsing of the submerged combustionburners, popping of large bubbles above submerged burners, ejection ofthe molten matrix from main matrix melt against the walls and ceiling ofmelt vessel 601, and the like. Melter exit structure 628 comprises afluid-cooled transition channel 30, having generally rectangularcross-section in melt vessel 601, although any other cross-section wouldsuffice, such as hexagonal, trapezoidal, oval, circular, and the like.Regardless of cross-sectional shape, fluid-cooled transition channel 630is configured to form a frozen matrix layer or highly viscous matrixlayer, or combination thereof, on inner surfaces of fluid-cooledtransition channel 630 and thus protect melter exit structure 628 fromthe mechanical energy imparted from the melt vessel 601 to melter exitstructure 628. This disclosure described some aspects of the presenttechnology with reference to the accompanying drawings, in which onlysome of the possible aspects were shown. Other aspects can, however, beembodied in many different forms and should not be construed as limitedto the aspects set forth herein. Rather, these aspects were provided sothat this disclosure was thorough and complete and fully conveyed thescope of the possible aspects to those skilled in the art.

Although specific aspects were described herein, the scope of thetechnology is not limited to those specific aspects. One skilled in theart will recognize other aspects or improvements that are within thescope of the present technology. Therefore, the specific structure,acts, or media are disclosed only as illustrative aspects. The scope ofthe technology is defined by the following claims and any equivalentstherein.

What is claimed is:
 1. A system comprising: a melt vessel configured toreceive a material and melt the material into a matrix, the melt vesselincluding: a base; a feed end wall defining a feed port for receivingthe material; an exit end wall defining an exit port allowing egress ofthe matrix; and a roof, wherein the base, the feed end wall, the exitend wall, and the roof form a substantially closed volume; a transitionchannel in fluid communication with the exit port for receiving thematrix from the exit port; a plurality of burners disposed so as topenetrate the base, wherein at least one of the plurality of burnerscomprises: a toroidal burner tip defining an outlet for delivering thecombustion gases into the substantially closed volume; a portion exposedto the matrix, wherein the portion of the burner exposed to the matrixincludes a plurality of polished features having heights not greaterthan 1 micron.
 2. The system of claim 1, wherein the portion exposed tothe matrix comprises the toroidal tip.
 3. The system of claim 1, whereinthe portion exposed to the matrix comprises a burner body.
 4. The systemof claim 1, wherein the plurality of polished features have heights ofless than about 0.5 micron.
 5. A system comprising: a melt vesselconfigured to receive a material and melt the material into a matrix,the melt vessel including: a base; a feed end wall defining a feed portfor receiving the material; an exit end wall defining an exit portallowing egress of the matrix; and a roof, wherein the base, the feedend wall, the exit end wall, and the roof form a substantially closedvolume; a transition channel in fluid communication with the exit portfor receiving the matrix from the exit port; a plurality of burnersdisposed so as to penetrate the base, wherein at least one of theplurality of burners comprises a welded portion having a void fractionof less than about 1%.